1. Field of the Invention
The present invention relates to an apparatus for controlling an internal combustion engine of a motor vehicle in which an accerelator pedal and a throttle valve are not mechanically linked together but interconnected electrically.
2. Description of the Prior Art
In the hitherto known motor vehicles, the accerelator pedal and throttle valve are mechanically linked in such a manner that when the accelerator pedal is depressed, the throttle valve is opened correspondingly, whereby the output power of the engine is controlled. In the case of this type engine control system, the fuel injection pulse width is determined by dividing the number of cycles of rotation of the engine by the amount of air flow supplied to the engine. Reference may be made, for example, to Japanese Patent Unexamined Publication No. 57-59039 (JP-A-No. 57-59039).
In most of the hitherto known motor vehicles, when the throttle valve is opened, the amount of air flow corresponding to the opening degree of the throttle valve is supplied to the engine without any appreciable delay. In contrast, with respect to the fuel, there can not always be obtained the amount of fuel which corresponds to the abovementioned amount of air flow, because of a delay or similar factor intervening between the detection of the amount of air and the engine rotation number, resulting in an undesirable influence on the operation performance of the engine.
Further, the operation performance of the engine and hence the motor vehicle is more or less degraded because of changes occurring in the rotation number even in the course of driving at a constant speed under the influence of non-uniform combustion and road conditions. However, no consideration has heretofore been paid to this problem. In other words, preference is put on the air flow control, which often results in improper A/F ratio transiently, accompanied by variations in the engine rotation number and the bumping of the motor vehicle during constant speed operation, and hence discomfort in driving the car occurs.